Chuck Liddell has ridiculed the odds-makers who have made Rashad Evans a huge underdog against Jon Jones at UFC 145, insisting there is one massively important factor at play this weekend: The challenger knows the champion is not invincible.

Jones puts the UFC light-heavyweight title on the line on April 21, and only the boldest punter is rushing to back against him. The champ has never been beaten, other than a sole disqualification in the act of winning.

Evans, however, rarely makes a habit of losing either. Only Lyoto Machida has defeated him, and the No. 1 contender has the advantage of having previously trained with Jones.

Liddell, the former 205lb champion, does not buy into the suggestion that either man knows what the other will do as a result of their history together. However, he is convinced it will stop Evans taking any fear into the Octagon, as the likes of Rampage Jackson and Lyoto Machida may have done.

"I don't know who it affects, the fact that they've trained together, I'm not even sure it does affect it," Liddell told ESPN. "Some guys are gym fighters, some guys are better in the ring. However, it is always interesting when guys have trained together before.

"The fact is people talk about Jon Jones having an aura of invincibility but when you've trained together as much as they have that goes out the window. That part of the fight is maybe a new thing for Jones."

Liddell, who continued to work with the UFC after his decision to retire, admits he has spoken with both Jones and Evans prior to fight night. And the Iceman insists Evans is not putting on any pre-fight hype - he is every bit as confident as he looks.

"It's a huge fight, it's going to be a tough fight for Jon, to see if he can continue his reign and his dominance. He's 1/5 or 1/6 favourite but it's a tough fight for him - Rashad is a tough fighter," Liddell said.

"I've spoken to Rashad and he's very confident. Rashad thinks he can push him - he's so confident about that.

"Just talking to Rashad, it doesn't sound like he's putting anything on. He's just confident. I wouldn't comment if it was just an interview, but I actually spoke to him and he is extremely confident."